The present invention is related to a battery pack used in a battery of an electronic device, particularly to a battery pack and its fabricating method which can eliminate influence of electrostatic discharge, as well as a battery assembled with the same battery pack and an electronic device equipped with the same battery.
In recent years, battery packs have been used as power sources for mobile electronic devices. In such battery packs, an outer package houses a battery cell, and a protection circuit board on which a protection circuit and the like are mounted. As an outer package used for such a battery pack, a box-shaped package comprising upper and lower cases and the like is widely used.
However, in the battery pack described above, when electrostatic discharge (ESD) occurs, static electricity may flow in the circuit board inside the battery pack, resulting in a malfunction of electronic circuits or damage to semiconductor elements. Furthermore, when the battery pack described above is contained and used in an electronic device, such as a mobile phone, functional failure may be caused in the body of the electronic device due to the occurrence of ESD. Especially in the case where the body of the electronic device has a structure having low tolerance to electrostatic discharge, there is a high probability of occurring functional failure.
FIG. 12 is a schematic view showing a battery pack housing part of an electronic device, such as a mobile phone. As shown in FIG. 11, usually the battery pack housing part 101 is provided with an opening 102, and a circuit board of the electronic device is exposed through the opening 102. In the electronic device having such a structure, when ESD occurs, there is a possibility that a conductive layer disposed on the surface of the outer package may form a static electricity path, and static electricity may flow in the circuit board exposed through the opening 102, resulting in a malfunction of electronic circuits or damage to semiconductor elements.
In order to solve the above problems, for example, a solution is disclosed in a Chinese patent application with publication number CN101651235A. FIGS. 13A to 13D are schematic views showing a method of assembling a battery pack in prior art. As shown in FIG. 13A, a conductive tape 30a is introduced into a battery pack, and one end of the conductive tape 30a is connected to a positive electrode lead 5a which is led out from a battery cell 4. Then, as shown in FIG. 13B, the other end of the conductive tape 30a is placed on an upper surface of a top cover 2. Next, as shown in FIG. 13C, while appropriately folding the positive electrode lead 5a and the negative electrode lead 5b, the top cover 2 is fitted into a top opening of the outer package 1. Thereby, as shown in FIG. 13D, the top opening of the outer package 1 is closed by the top cover 2, and the other end of the conductive tape 30a is clamped between a hard lamination of the outer package 1 and the top cover 2. Heater blocks composed of a metal, such as copper, are pressed against the upper and lower sides at the vicinity of the top of the outer package 1, and the periphery of the top cover 2 and a polypropylene layer within the hard lamination are heat-welded. Thereby, the polypropylene layer is melted, and the other end of the conductive tape 30a, which is clamped between the upper surface of the top cover 2 and the outer package 1, is electrically connected to a hard aluminum metal layer within the hard lamination. Similarly, heater blocks may be pressed against the upper and lower sides at the vicinity of the bottom of the outer package 1, and the periphery of the bottom cover 3 and the polypropylene layer within the hard laminate may be heat-welded. Consequently, by connecting a conductive layer of the lamination to a positive electrode terminal or a negative electrode terminal of the battery pack, the tolerance to ESD is improved.
However, the technologies in the above-mentioned documents have problems as below. First of all, by the way of using a conductive tape for connecting, it only can be conducted after a battery pack is accomplished and put into an assembling stage, which adds additional procedures and is difficult to guarantee reliability of the battery pack. Moreover, due to complex processes, the requirements for the assemble staff are extra increased, thereby production efficiency is reduced.